If there are going to be contested results, you will see the crisis developing.

Hotspots to watch: Missouri, where there always seem to be problems in St Louis, as well as Pennsylvania (especially the Philadelphia area), Ohio, Florida, Virginia, North Carolina, Colorado and Nevada.

These are states that have seen significant patterns of complaint and concern going into election day.

3. Watch Kentucky.

Long queues can make it hard for working people to spare the time to vote [Reuters]

When the actual results start coming in, don't just pay attention to the battleground states.

Early returns from the state of Kentucky, where the polls close in most of the state at 6pm EST (23:00 GMT) and where McCain is thought to be well ahead, will provide important indications.

A projection will not come immediately, as a portion of the state keeps polls open until 7pm EST (00:00 GMT).

But the count and projection should come more quickly in this state than any other. And it could be meaningful.

For instance, if Kentucky is not quickly projected for the Republican, that means that Obama is running better than expected.

If, when results become available, the Democrat is at 45 per cent or better, bet that he will win states such as Indiana, Ohio and West Virginia.

If Obama wins Kentucky, start thinking "landslide."

4. Bonus round

If Senate minority leader Mitch McConnell, Republican-Kentucky, loses, then the Democrats are on track for a Senate super-majority, which will allow them to block Republican delaying tactics such as filibusters on proposed legislation.

5. Virginian upset

When all the polls are closed at 7pm EST (00:00 GMT) in Indiana and Virginia, we'll begin to get a clear picture of whether Obama's 50-state strategy is working.

If either state declares quickly for the Democrat, that is hugely significant.

Obama is expected to win Virginia, but if his margin is wide enough to put the state in his column early in the evening, then he is making movement that could be significant, not just in Virginia, but in neighbouring North Carolina.

On the other hand, if McCain wins Virginia, then the Republican is beginning to put together the pieces of an upset.

If anything, Indiana is even more significant than Virginia.

Solidly Republican in presidential politics since 1964, Indiana was not supposed to be competitive this year. But it is.

And if Obama secures the state early in the evening, his chances of winning neighbouring Ohio – as well as another battleground state, West Virginia – will look a whole lot better.

6. Watch the congressional race

Another 7pm EST (00:00 GMT) closing is in South Carolina. Don't look for an Obama win here, but watch a congressional race.

Republican congressman Henry Brown is in a tight contest with Democrat Linda Ketner, who has rewritten a lot of political rule books this year.

If Ketner wins, which polls suggest is possible, the Democratic congressional campaign committee's strategy on recruiting candidates and targeting resources in a wider range of districts is working.

In the neighbouring state of Georgia, where polls also close at 7pm EST, watch the senate race: incumbent Republican Saxby Chambliss is vulverable; if he loses outright or is forced into a run-off (required under state law if no one gets a majority), the Democratic senate campaign committee will be popping champagne corks early.

In the results from South Carolina and Georgia, we will get the first clear read on the role a dramatic increase in African-American turnout might play in presidential and congressional contests - especially in states that were not expected to be competitive.

Don't expect quick results from Pennsylvania. The Keystone State does not "do" early voting, so the lines will be long and tens of thousands of voters may still be in line (and eligible to vote) when the official closing time comes.

The same goes for Missouri.

Best hope for early indicators: New Hampshire. Did McCain take it back for the Republicans? He probably has to do so in order to win.

Keep an eye, as well, on South Dakota, the Central Time half of which reports at 8pm EST (01:00 GMT), while the Mountain Time half reports at 9pm (02:00 GMT).

A small state that counts quickly, South Dakota could give one of the first signals about whether Obama's western strategy is succeeding in repainting traditionally red states blue.

8. North Carolina

At 8:30pm EST (01:30 GMT), polls in North Carolina close.

Did the state go Democratic in a presidential race for the first time since 1976?

Equally significant: Did Republican senator Elizabeth Dole, who closed her campaign on a particularly vicious note of religious intolerance, lose?

If Democrat Kay Hagan beats Dole, a President Obama is all but certain to have an overwhelmingly Democratic senate - perhaps even the filibuster-proof one that he barely dared imagine just weeks ago.

9. Time to declare a national winner

At 9pm EST (02:00 GMT), 15 more states finish voting. More than 430 of the 538 electoral votes will be accounted for.

As results become available from Colorado, New Mexico and newly competitive Arizona, and if votes are being counted quickly, it will now be possible to declare a national winner.

If Obama takes Colorado and New Mexico on top of a solid pattern of east-of-the-Mississippi wins, he will be president.

If he takes McCain's home state of Arizona, his victory will be capped with delicious irony.

Don't forget to vote [AFP]

10. Play Hardball

The 9pm EST (02:00 GMT) batch of states will also provide key indications regarding Democratic prospects in congress.

Did McCarthyite Republican congresswoman Michele Bachmann lose her Minnesota district to challenger Elwyn Tinklenberg, whose campaign took off after Bachmann started ranting on MSNBC's Hardball in late October?

Did Democrats pick up the open Minnesota House seat being sought by Iraq war vet Ashwin Madia?

Wins in those districts would point to major pick-ups - perhaps more than 30 seats overall for Speaker Nancy Pelosi's House Democrats.

Similarly, if Democrat Al Franken - who campaigned hard in the large Somali community of the Twin Cities - displaces Republican incumbent Norm Coleman in Minnesota's intense US senate race, Democrats will be on track to dominate the upper chamber (And Franken's nemesis, Bill O'Reilly of Fox News, will not be happy.)

11. Last-minute touches

In the states with 10pm EST (03:00 GMT) closing times, watch Iowa and Nevada.

The campaigns put last-minute time and resources into both states, although Iowa appeared to be safely in the Democratic column.

If Obama wins Iowa and turns Nevada red to blue, one of these states might put him over the top. But that is only because the big-ticket state of California, which also reports at 10pm EST, will take longer to count.

When the numbers are known, however, we will be reminded why Republican Governor Arnold Schwarzenegger made his big campaign stop for McCain in Ohio, not California.

The Golden State is solid blue.

12. Bonus round

Will Ron Paul's votes on the Constitution party ballot line in Montana cost McCain a state that has long leaned Republican in presidential contests but has been trending Democratic?

Paul's signs are everywhere in Montana, and if he takes four or five per cent of the vote, it could be just enough to tip the state to Obama.

13. As the end draws near

At 11pm EST (04:00 GMT), when Washington state is finished voting and all the precincts in neighbouring Oregon are shuttered, watch for a pair of congressional results.

Did Democrat Jeff Merkley defeat Republican senator Gordon Smith, who tried to run as a moderate (going so far as to link himself with Obama in GOP television ads)?

Did Darcy Burner, a progressive Democrat who ran on a strong, anti-war platform, grab a Republican-held seat outside Seattle?

Both wins would signal not just that Democrats are winning congressional races, but that the next Democratic caucuses will tilt to the left of the old ones.

14. Alaska

Finally, if you can't get enough of Election 2008, the last polls remain open in Alaska until 1am EST (06:00 GMT) on Wednesday.